h263: disable slow checked reader, overreads are not possible in

ffmpegs h263 decoder
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/h263dec.c

@@ -25,6 +25,8 @@
  * H.263 decoder.
  */
 
+#define UNCHECKED_BITSTREAM_READER 1
+
 #include "libavutil/cpu.h"
 #include "internal.h"
 #include "avcodec.h"

libavcodec/ituh263dec.c

@@ -27,6 +27,8 @@
  * h263 decoder.
  */
 
+#define UNCHECKED_BITSTREAM_READER 1
+
 //#define DEBUG
 #include <limits.h>